Field of the Invention
The present invention relates to a method of converting of particles liberated in chemical or physical processes into harmless form by mixing these particles with molten silicate-containing material, after which the mixture as obtained is allowed to solidify and is, if desired, reduced in size.
A method of this type is known. In this method dust particles containing for example, zinc, cadmium and/or copper and/or possibly other metals and being liberated in feeding ore granules obtained by pelletization to a blast furnace are made harmless by mixing with a liquid stream of metallurgical slag material tapped off from a blast furnace. The dust particles are added in a quantity of 25% based on the stream of slag material.
The trapping in said manner of dust particles being generated in the reduction of a phosphate-containing ore with carbon in a chemical furnace and mixing them in an amount of 25% with liquid phosphorus-furnace slag are also known.
In using these amounts of dust particles the collected particles as added melt completely in the molten slag material.
A drawback of this method is that if powdery materials comprising particles being very voluminous and/or having very porous surface structure are used, only relatively small amounts of particles can be absorbed in the slag if it is desired to allow the particles to melt in the slag or if this melting requires a long time.
As examples of such particles, particles obtained by drying sludge from electroplating processes, sludge from the preparation of metal or metal hydroxide, fly ash and the like may be cited.
As a result of the air being present around said particles or occluded in the masses of said particles, said particles have particularly the tendency only to be well absorbed at the interface between molten silicate-containing material and the particles.
It even occurs frequently that as a result of the sudden heating up of the air being present around the particles, said particles are "blown away" from the surface of the slag or even out of the slag mass.